‘Lydia’ is a product of a breeding and selection program for outdoor pot mums (garden mums) which had the objective of creating new chrysanthemum cultivars with a decorative type flower, a natural flowering date late in autumn; blooming for a period of 5 weeks. The new plant of the present invention comprises a new and distinct cultivar of chrysanthemum plant; ‘Lydia’ is a seedling resulting from a crossing program, set up by a previous breeder, and which records are unknown to the inventor. The new and distinct cultivar was discovered and selected as a flowering plant by Mark Roland Boeder on a cultivated field in Rijsenhout, The Netherlands in 2001. The first act of asexual production of ‘Lydia’ was accomplished when vegetative cuttings were taken from the initial selection in 2001 and propagated further in a controlled environment in Rijsenhout, The Netherlands. The new cultivar has been found to retain its distinctive characteristics through successive propagations.